Improved bacteriological surveillance of haemodialysis fluids: a comparison between Tryptic soy agar and Reasoner's 2A media

Background. Accurate microbiological surveillance in haemodialysis centres is important as end-stage renal patients can suffer from pyrogenic reactions due to bacterial contamination of dialysis fluids. To evaluate the microbiological quality of haemodialysis fluids, special nutrient-poor culture techniques are necessary. Although the Association for the Advancement of Medical Instrumentation (AAMI) recommends Tryptic soy agar (TSA) as the standard agar, several studies have resulted in a general preference for Reasoner's 2A (R2A) agar, as it appeared to be more sensitive in demonstrating contamination of typical haemodialysis associated bacteria. In the Netherlands TSA is still used for culturing dialysate, while dialysis water is cultured on R2A. Therefore, the aims of our study were to evaluate bacterial yields of dialysis fluids on both media, and to qualify their use in routine microbiological monitoring within our haemodialysis centre.